variable x equal "xlo + 0.25*lx"-
Similarly, these variable definitions will move the indenter at a -constant velocity: +
Similarly, either of these variable definitions will move the indenter +from an initial position at 2.5 at a constant velocity of 5:
-variable x0 equal 2.5 -variable vx equal 5.0 -variable x equal "v_x0 + step*dt*v_vx" +variable x equal "2.5 + 5*elaplong*dt" +variable x equal vdisplace(2.5,5)If a spherical indenter's radius is specified as v_r, then these variable definitions will grow the size of the indenter at a specfied diff --git a/doc/fix_indent.txt b/doc/fix_indent.txt index eacdb72d4b..65811ef770 100644 --- a/doc/fix_indent.txt +++ b/doc/fix_indent.txt @@ -113,12 +113,11 @@ the right edge, even if the box size changes: variable x equal "xlo + 0.25*lx" :pre -Similarly, these variable definitions will move the indenter at a -constant velocity: +Similarly, either of these variable definitions will move the indenter +from an initial position at 2.5 at a constant velocity of 5: -variable x0 equal 2.5 -variable vx equal 5.0 -variable x equal "v_x0 + step*dt*v_vx" :pre +variable x equal "2.5 + 5*elaplong*dt" +variable x equal vdisplace(2.5,5) :pre If a spherical indenter's radius is specified as v_r, then these variable definitions will grow the size of the indenter at a specfied diff --git a/doc/region.html b/doc/region.html index 0978c4926e..1f291ccd07 100644 --- a/doc/region.html +++ b/doc/region.html @@ -13,7 +13,7 @@
Syntax:
-region ID style args keyword value ... +region ID style args keyword arg ...
side value = in or out
in = the region is inside the specified geometry
@@ -60,15 +60,12 @@
units value = lattice or box
lattice = the geometry is defined in lattice units
box = the geometry is defined in simulation box units
- vel args = Vx Vy Vz
- Vx,Vy,Vz = components of velocity vector (velocity units)
- wiggle args = Ax Ay Az period
- Ax,Ay,Az = components of amplitude vector (distance units)
- period = period of oscillation (time units)
- rotate args = Px Py Pz Rx Ry Rz period
- Px,Py,Pz = origin point of axis of rotation (distance units)
- Rx,Ry,Rz = axis of rotation vector
- period = period of rotation (time units)
+ move args = v_x v_y v_z
+ v_x,v_y,v_z = equal-style variables for x,y,z displacement of region over time
+ rotate args = v_theta Px Py Pz Rx Ry Rz
+ v_theta = equal-style variable for rotaton of region over time (in radians)
+ Px,Py,Pz = origin for axis of rotation (distance units)
+ Rx,Ry,Rz = axis of rotation vector
Description:
@@ -94,13 +91,12 @@ surface of the region can be used as a boundary wall via the vel or wiggle or -rotate keyword is used, as described below, the region becomes -"dynamic", meaning it's location or orientation changes with time. -This may be useful, for example, when thermostatting a region, via the -compute temp/region command, or when the fix wall/region command uses -a region surface as a bounding wall on particle motion, i.e. a -rotating container. +extent does not change with time. If the move or rotate keyword +is used, as described below, the region becomes "dynamic", meaning +it's location or orientation changes with time. This may be useful, +for example, when thermostatting a region, via the compute temp/region +command, or when the fix wall/region command uses a region surface as +a bounding wall on particle motion, i.e. a rotating container.The delete style removes the named region. Since there is little overhead to defining extra regions, there is normally no need to do @@ -131,7 +127,7 @@ of the simulation box. regardless of whether the dimension of a simulation is 2d or 3d. Thus when using regions in a 2d simulation, you should be careful to define the region so that its intersection with the 2d -x-y plane of the simulation is the 2d geometric object you want. +x-y plane of the simulation has the 2d geometric extent you want.
For style cone, an axis-aligned cone is defined which is like a cylinder except that two different radii (one at each end) can be @@ -232,44 +228,59 @@ applied to the sphere radius.
If the vel or wiggle or rotate keywords are used, the region -is "dynamic", meaning its location or orientation changes with time. -No more than one of these keywords can be used at a time. These -keywords cannot be used with a union or intersect style region. -Instead, the keywords should be used to define the individual -sub-regions of the union or intersect region. Normally, each -sub-region should be "dynamic" in the same manner (e.g. rotate around -the same point), though this is not a requirement. +
If the move or rotate keywords are used, the region is "dynamic", +meaning its location or orientation changes with time. These keywords +cannot be used with a union or intersect style region. Instead, +the keywords should be used to make the individual sub-regions of the +union or intersect region dynamic. Normally, each sub-region +should be "dynamic" in the same manner (e.g. rotate around the same +point), though this is not a requirement.
-The vel style moves the region at a constant velocity, so that its -position X = (x,y,z) as a function of time is given in vector -notation as +
The move keyword allows one or more equal-style +variables to be used to specify the x,y,z displacement +of the region, typically as a function of time. A variable is +specified as v_name, where name is the variable name. Any of the +three variables can be specified as NULL, in which case no +displacement is calculated in that dimension.
-X(t) = X0 + V * delta +Note that equal-style variables can specify formulas with various +mathematical functions, and include thermo_style +command keywords for the simulation box parameters and timestep and +elapsed time. Thus it is easy to specify a region displacement that +change as a function of time or spans consecutive runs in a continuous +fashion. For the latter, see the start and stop keywords of the +run command and the elaplong keyword of thermo_style +custom for details. +
+For example, these commands would displace a region from its initial +position, in the positive x direction, effectively at a constant +velocity: +
+variable dx equal ramp(0,10) +region 2 sphere 10.0 10.0 0.0 5 move v_dx NULL NULL-where X0 = (x0,y0,z0) is its position at the time the region is -specified, V is the specified velocity vector with components -(Vx,Vy,Vz), and delta is the time elapsed since the region was -specified. +
Note that the initial displacemet is 0.0, though that is not required.
-The wiggle style moves the region in an oscillatory fashion, so that -its position X = (x,y,z) as a function of time is given in vector -notation as +
Either of these varaibles would "wiggle" the region back and forth in +the y direction:
-X(t) = X0 + A sin(omega*delta) +variable dy equal swiggle(0,5,100) +variable dysame equal 5*sin(2*PI*elaplong*dt/100) +region 2 sphere 10.0 10.0 0.0 5 move NULL v_dy NULL-where X0 = (x0,y0,z0) is its position at the time the region is -specified, A is the specified amplitude vector with components -(Ax,Ay,Az), omega is 2 PI / period, and delta is the time -elapsed since the region was specified. -
-The rotate style rotates the region around a rotation axis R = -(Rx,Ry,Rz) that goes thru a point P = (Px,Py,Pz). The period of -the rotation is also specified. The direction of rotation for the -region around the rotation axis is consistent with the right-hand +
The rotate keyword rotates the region around a rotation axis R = +(Rx,Ry,Rz) that goes thru a point P = (Px,Py,Pz). The rotation +angle is calculated, presumably as a function of time, by a variable +specified as v_theta, where theta is the variable name. The variable +should generate its result in radians. The direction of rotation for +the region around the rotation axis is consistent with the right-hand rule: if your right-hand thumb points along R, then your fingers wrap around the axis in the direction of rotation.
+The move and rotate keywords can be used together. In this case, +the displacement specified by the move keyword is applied to the P +point of the rotate keyword. +
Restrictions:
A prism cannot be of 0.0 thickness in any dimension; use a small z @@ -283,7 +294,7 @@ parameters must be 0.0.
Default:
-The option defaults are side = in, units = lattice, and no -velocity, wiggling, or rotation. +
The option defaults are side = in, units = lattice, and no moving or +rotation.